1. Field of the Invention
This invention relates in general to semiconductor devices and more specifically to the formation of semiconductor devices with separately formed layers.
2. Description of the Related Art
In some integrated circuits, it is desirable to form corresponding layers of different devices at different times and/or of different materials. One example is in the formation of the gates of P-channel type and N-channel type transistors of an integrated circuit. It may be desirable to have the gate of the P-channel type transistor be of one material and the gate of the N-channel type transistor to be of a second material to provide each transistor with a different threshold voltage.
However, there are challenges in forming such structures with conventional methods. What is desired is an improved technique for forming an integrated circuit with corresponding structures of different materials.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. The Figures are not necessarily drawn to scale.